Heater Control Unit
 

My 1985 grey market 930 has a heater control unit between the seats. The heater box cable is operated by a servo motor, no lever. It isnt working for me. I have the control unit out. Potentiometer is fine. switches on the dial fine. Getting 12v to the unit, but not getting any action out of the motor.

Anyone know how to diagnose the control unit on the bench?

Pelican Parts Technical BBS - Search Results
This may help.
I had the same issue.
Ended up just going with the lever.

By '85 they had done away with the lever entirely.
Wish it were there. In fact, I would gladly trade the whole mess for the lever on an early 911.
Thanks for the link. Much very helpful info.

Yes, my car still has the lever.
So I could just disconect the HCU ( remove one screw) and use the lever.
Going back to a lever is not a bad option for you.
Its an easy install and does away with the drama.

heater control unit
 

Amazingly, I got the unit working on the bench. I need new sockets, which I found, and the little light bulb, which I havent found. Anyone see this for sale?

Good news.
Well done. :)